“Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.” – Mark Twain

Strange Electrical Issue – Update

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I did a previous post about a strange issue I had on our AC power side.  I got some feedback from my go-to marine electrician, Compass Marine aka Maine Sail, that he suspected the GFCI outlets were bad.  These items should be considered disposable items that should be replaced every few years.  He also gave me some good advice about what manufactures and qualities to look for in a decent GFCI outlet.

After striking out in finding any of the GFCI outlet’s recommended at 3 local electrical supply houses.  I ordered the new GFCI outlets from Amazon. I went with the Hubbell GFTR 15. It’s a commercial grade, tamper resistant, weather resistant, UL 943 Class A GFCI receptacle.

This morning I dove into replacing the outlets and confirming the wiring.

I started with the outlet in the galley.  This one was easily accessible and the wiring was as expected.


Existing Wiring


Old Outlet on right (Hubbell Class A UL 943). New Outlet on left (notice the TR and WR)

My wiring hint for any other novices, label each leg in pairs so you don’t confuse them.  I use the Ideal Wire Marking Booklet. I purchased this booklet over 10 years ago for about $25 and have used it for many projects on the boat and in the house before we sold it.  IMG_2484

I like to label my wiring legs with the same number.  So the positive, negative and ground would be labeled the same.  The other end of the leg would get the same labels too. So that means you would need 6 of the same number to label the leg completely with 12-3 marine cable that was run by Catalina.


For this project I put the labels on the terminal.  Mainly because I am not entirely thrilled with what Catalina used.  I would prefer ring terminals with adhesive heat shrink.  So when I fix the problem I found (see below) I will probably change over to ring terminals.

I completed the change on the first outlet without an issues.

When I took out the second outlet I found an issue.  According to the wiring diagram provided by Catalina, this should have been a single leg outlet with only a feed line connected to the top of the outlet and nothing connected to the bottom, load side.  Well it was connected on both sides.  I tried to look around and figure out exactly how everything was run.  However, all of the wires were bundled in wire loom and I couldn’t follow it easily.  It’s a little cool out and the temp in the cabin had dipped below 55 degrees so I decided to just put the new outlet in and then figure out how the wires were run.

I re-energized the outlets and checked to make sure I wired everything correctly.  I used an outlet tester to make sure I had the polarity and ground connected correctly.


Two yellow lights and no red mean it done right.

I then went through all the outlets and figured out what order they were wired and what the GFCI’s affected.  Here is a revised wiring diagram based on what I found.  C310 115VAC Wiring Diagram_V2 C310 AC Plan_V2

So all 6 outlets are on a single leg of outlets and the 1st and 3rd outlets in line are GFCI.  This is incorrect wiring and probably responsible for part of the strange issue I was having.  At the very least it’s a redundant GFCI.

My plan is to split the outlets into two legs.  I think I will have outlets #1 and #2 on leg one and outlets #3 – #6 on the other leg.  This would mean running a new 12-3 wire from the electric panel to that outlet.  And then disconnecting the wires that run from outlet #2 to outlet #3.  I am not a big fan of keeping unused wires in place so I will remove the old wires.

But now I am wondering if this is necessary.  All the outlets are fed by the single 30 amp breaker.  If I split the legs, both legs would still be fed by the 30 amp breaker.  So is there any benefit from separating the legs?

If not, I could just remove the second GFCI outlet and replace it with a standard outlet.  I could then save the GFCI outlet for next time I need to replace GFCI outlet #1.

After replacing the outlets I ran heaters, electric tea kettle, microwave, iron and dehumidifier at various times and levels and didn’t have any of the issues I was having before replacing the outlets.  I did pop the outlet breaker at the panel once when I ran the heater on high with the microwave by mistake.

At this point I am guess that I have at least one more update before I put this project to bed.

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